A woman who helped arsonists carry out a petrol bomb attack on a family home - killing four children - has launched a bid to be freed from prison.

Courtney Brierley worked alongside her then boyfriend, Zak Bolland, and his accomplice, David Worrall, to help set fire to the house in Walkden, Greater Manchester.

Demi Pearson, 15, and her siblings Brandon, eight; Lacie, seven; and three-year-old Lia were all killed. Their mother Michelle, 36, was rescued but was seriously hurt.

The attack was the devastating climax to a feud involving Bolland and Kyle Pearson, Michelle Pearson's eldest son, who escaped the blaze.

Lia Pearson, three, was killed in the arson attack (Image: PA)

Demi Pearson, 15 (Image: PA)

Brandon and Lacie Pearson were both killed in the fire (Image: PA)

Now Brierley, 20, who was sentenced to 21 years behind bars for manslaughter, has lodged an appeal against her conviction and sentence.

A woman who claims to have served time with Courtney Brierley told the Manchester Evening News that the 20-year-old was 'broken' behind bars.

One prisoner, now released, said: "Courtney was very, very quiet, very broken.

"I didn't know what she'd done until after I'd left and I was horrified, you just would not have thought it of her."

She described how Brierley was housed in a block with lifers.

Zac Bolland and Courtney Brierley were both convicted (Image: z.bolland/Instagram)

"Courtney came straight in on remand and was put in a single cell which she rarely left.

"She was employed as a cleaner but was always being chased by senior prison officers to come and do her work," said the woman.

She added: "She always looked like she'd been crying, was very, very quiet, didn't make friends with anyone, rarely ate.

"She was completely broken and received a lot of one to one time in her cell from the prison officers."

Siblings Lia, Lacie and Brandon before they were killed (Image: PA)

When she was returned to the prison to begin her sentence following a period on remand there, Brierley was in a 'very bad way', the woman told us.

Courtney Brierley helped Zak Bolland and David Worrall carry out the attack on December 11 2017, urging them to put their hoods up as they purchased the petrol used in the firebombing and then going with them in the car that took them and the petrol bombs to Jackson Street in Walkden.

The damage to the house caused by Brierley, Worrall and Bolland (Image: Greater Manchester Police)

Brierley had claimed she acted because she was in fear of her violent and abusive boyfriend Bolland and had not realised exactly what he was about to do.

Following a trial at Manchester Crown Court, the jury found her not guilty of murder but convicted her of four counts of manslaughter.

She was sentenced to 21 years in a young offenders’ institution and can apply for parole halfway through her sentence.

Her legal team tried and failed to get the case against her thrown out mid-trial, arguing she had done little more than the prosecution’s main witness Abigail Toone, who had unwittingly acted as the trio’s getaway driver.

Bolland, 23, of Worsley, was jailed for a minimum of 40 years after he was convicted of murder at the conclusion of that trial, which heard he threw a large petrol bomb into the house through a rear window as the family slept.

His friend Worrall, 26, also of Worsley, had thrown a smaller petrol bomb into the house but it had not caused significant damage.

He was caged for a minimum 37 years after being convicted of murdering the children.